This invention relates to a method and a device for determining the spatial position of a sensor, in particular for determining the translatory and rotatory position of a 3D sensor for the three-dimensional digitization and/or three-dimensional measurement of large objects.
A method for the three-dimensional digitization (3D digitization) of objects is known for instance from DE 10 2005 043 912 A1. For 3D digitization a 3D sensor is used, which determines the three-dimensional coordinates (3D coordinates) of the surface of an object. In general, it is necessary to move the 3D sensor in space into various recording positions, in order to assemble the entire object surface to be measured out of partial surfaces measured at the individual recording positions. Such assembly requires the registration of the individual recording positions in a superordinate coordinate system. This so-called global registration requires high accuracy.
When using a white-light strip projection system as a 3D sensor, it is known to carry out the global registration by means of photogrammetry. For this purpose, marks must be provided on the object or on a link and be measured separately with a photogrammetry equipment. Photogrammetry offers high accuracy, but is disadvantageous because of the additional effort for preparation with the marks and the separate measurement thereof.
Furthermore, it is known to measure the position of the 3D sensor with a laser tracker, so as to carry out the global registration of each individual recording position by means of these measurement data. For this purpose, at least three suitable reflectors must be mounted on the 3D sensor, and in each recording position of the 3D sensor, the reflectors must be measured successively with the laser beam of the laser tracker. The measurement data of the laser tracker allow a global registration with the highest accuracy. What is disadvantageous, however, is the time-consuming detection of the reflectors in space after repositioning the sensor, which increases the time required for digitizing the measurement object.